Prime the feet and reactions. Move through the ladder with fast, light steps, explode out of the last rung, and receive and return the pass cleanly on the burst.
Set an agility ladder with a server and a receiving cone beyond it. The player performs a footwork pattern through the ladder (one or two feet per rung), explodes out of the last rung, and receives a pass from the server before returning it and jogging back. Keep the feet light and fast, and build the pace over the reps. Vary the ladder pattern each round.
Speed ladders do not make players faster and they do not make players more agile. The research is reasonably consistent on this and it contradicts most of what ladders are sold on, so it is worth saying plainly before describing how to use one. Agility in a match is a reaction to an opponent, and a fixed pattern of steps through a flat ladder trains no part of the reacting.
What a ladder is genuinely good for is priming. Fast, light contacts with the ground wake the nervous system up, get players onto the balls of their feet, and lift the tempo of a session in a way that is simple to organise and that children enjoy. As the second or third element of a warm-up, before anything explosive, that is a perfectly sound reason to own one.
So use it for what it does and keep it short. Three or four minutes of quick feet is priming. Fifteen minutes of increasingly elaborate ladder patterns is a coach filling time with something that resembles training and produces very little.
The technical points worth insisting on are the ones that transfer. Stay tall, drive the arms, stay on the balls of the feet, and get the eyes up rather than watching the rungs. A player who can only do quick feet while staring at the floor has learned a party trick.
The exit is the useful part. Explode out of the last rung into a sharp change of pace and take the pass on the burst, because that transition from small steps to full stride is the one element here that resembles football.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.